What is rumen acidosis?
The normal pH of a cow’s rumen is between 6.5 and 7.0. Rumen acidosis occurs when the pH falls below this level.
The fall in pH can take the rumen through sub-clinical to full clinical acidosis at which stage the rumen pH will have decreased to below 5.5. While clinical acidosis can usually be observed clearly, sub-clinical acidosis may be more difficult to recognize. As a consequence of the reduction in rumen pH, rumen flora (bacteria and protozoa) that is vital to the cow partly dies or can no longer function efficiently.
It is essential to have a healthy rumen flora. The flora ensures that feed is converted into useful nutrients for the cow. These nutrients are necessary as a source of energy and for the production of fats, proteins, carbohydrates and other elements that are vital to digestive processes, fertility, health and milk production.
Signs of rumen acidosis
- reduced cudding
- poor rumen fill (cow looks empty)
- reduced body condition
- reduced dry matter intake
- reduced milk production
- reduced butterfat percentage
- more undigested food parts in the dung
- tail swishing
- animals may also suffer hoof disorders
Rumen acidosis often starts during the transition period and gradually develops over the first 40-150 days of the lactation period. Fresh cows are particularly at an increased risk of subacute ruminal acidosis, since the rumen has not yet had the opportunity to adapt to a ration with higher energy content.
How to prevent rumen acidosis
The following are important to prevent rumen acidosis:
- Ensure a well-balanced transition diet is provided
- Lactation ration should be able to sustain increasing milk yield while providing sufficient amounts of effective fibre. Brewers Grains are useful sources of fibre.
- Feed should be accessible at all times day and night and pushing up the feed would be advisable.
- Use supplementary rumen buffers, such as sodium bicarbonate or live yeasts.
Measures in case of rumen acidosis
If a case of rumen acidosis is suspected, then it is important to intervene as quickly as possible. Possible interventions are:
- Reducing the proportion of rapidly fermentable carbohydrates (e.g. by reducing the proportion of wheat)
- Increasing the proportion of resistant starch in the ration, e.g. by adding maize.
- Slowing down the ration, e.g. by using brewers grains.
- Using rumen buffers.
Home grown cereals are more rumen friendly when crimped or caustic treated compared to rolled or milled, as they are converted more gradually in the rumen. The cattle need to be fed sufficient fibre.